On March 26 and 27, the U.S. Supreme Court will hear oral arguments in two cases challenging the definition of marriage as the union of one man and one woman. In Hollingsworth v. Perry, they will consider the constitutionality of the definition as enshrined in the California state constitution by voters in that state when they adopted “Proposition 8” in 2008 (effectively reversing the decision of the California Supreme Court to impose same-sex “marriage” earlier that year). In Windsor v. United States, they will consider the constitutionality of the same definition of marriage being adopted for all purposes under federal law through the 1996 Defense of Marriage Act (DOMA).

In anticipation of those oral arguments, I am running a series of blog posts with questions and answers related to the issue. Today, I look at the suggestion that support for redefining marriage is growing because more people have a loved one--a colleague, friend, or relative--who is openly homosexual. This was recently in the news because of the announcement by Sen. Rob Portman (R-Ohio) that he will now support marriage redefinition because his college-age son has said he is gay.

Here, we reprint an op-ed that I wrote last year with Regina Griggs of Parents and Friends of Ex-Gays and Gays.

Voters in 32 out of the 32 states where it has appeared on the ballot have upheld marriage as the union of a woman and a man. Advocates of same-sex marriage are holding out hope that their long losing streak will end on Election Day in Minnesota, Washington, Maryland or Maine.

Increasingly, advocates of same-sex marriage are abandoning legalistic arguments about "equality" and "civil rights," and appealing to emotion and personal relationships instead. "We (gays and lesbians) are your neighbors, your friends, your co-workers, your classmates and your relatives," the argument goes. "If you respect and care about us, how can you deny us what we want?" (namely, to have their same-sex relationships affirmed by the state through marriage licenses).

Polls suggest this approach is having an effect. People who know someone who self-identifies as "gay" or "lesbian" are more likely to support the redefinition of marriage than people who do not.

Is this connection a logical one? We argue it is not. How a person feels about their personal relationship with a gay friend, acquaintance, or relative should not dictate their position on the public policy issue of whether to change the definition of marriage.

We are both affiliated with Parents and Friends of Ex-Gays and Gays (PFOX), which spreads the truth that it is possible for sexual orientation to change, and defends the civil rights of ex-gays. Note, however, that the title of our organization includes the phrase, "and Gays." Many of those who look to PFOX for support are parents and/or friends of people who still self-identify as "gay" and engage in homosexual relationships. This is true of us personally as well. One of us (Regina) has an adult child who is openly gay. Peter and his wife have relatives and family friends who are gay as well.

It is a myth that disapproval of homosexual conduct equals "hate" toward homosexuals. If you are a parent, ask yourself – have you ever disagreed with your child? Have you ever disapproved of the behavioral choices she or he has made? The answer is surely "yes." Those experiences are not inconsistent with sincere love, and can actually be a manifestation of it.

I (Regina) continue to have a warm and loving relationship with my child and gay friends despite the fact that we disagree about whether homosexual relationships should be called "marriages."

My wife and I (Peter) had guests at our wedding who were divorced and who had children outside of wedlock. I do not approve of those actions any more than I do of homosexual conduct, but that does not interfere with my love for those people.

The myth that disapproval equals rejection stems from the myth that "being gay" is an intrinsic and immutable identity. Yet the decades-long search for a genetic or biological determinant of homosexuality has been a dismal failure.

This is not to say, however, that people "choose to be gay." Sexual orientation is an umbrella term for a person's sexual attractions, behavior and self-identification. People do not "choose" to experience homosexual attractions – but they do choose their behavior and self-identification.

Some people with same-sex attractions (SSA) choose to abstain from homosexual sex. Others seek professional help to change their sexual orientation, and many have succeeded. For a loved one to encourage those responses, rather than to affirm homosexual behavior, is just as loving as a parent or friend trying to encourage other choices they believe are in the person's best interest. Legalization of same-sex marriage would place an official stamp of approval on homosexual relationships, so any person who thinks that such homosexual attractions are changeable and that homosexual behavior is unhealthy will logically oppose this redefinition of marriage – no matter how much they may love a gay person.

However, opposition to the redefinition of marriage need not even rest on disapproval of homosexuality itself. The fundamental reason why marriage is treated as a public institution – and the reason it has always been defined as a male-female union – is the recognition that there is a unique role of heterosexual unions in reproducing the human race, and to keep the mother and father who create a child together to raise that child. Men and women are complementary in a way two persons of the same sex can never be. One need not consider homosexual relationships to be inferior in order to recognize that heterosexual ones are unique in their potential for natural procreation and the well-being of a child. While some same-sex couples raise children, such households are – by design – either motherless or fatherless. This is why even some openly gay people, like Maryland political activist Doug Mainwaring, oppose same-sex marriage.

We at PFOX urge everyone to love their gay friends and relatives unconditionally, and never to cut them out of your life just because they are gay. But personal relationships should not dictate the definition of our most fundamental social institution.